Rig time when making or extending a hole is a major cost item in creating a producing well and for that reason optimizing procedures to reduce the number of trips in the hole is the focus of constant efforts by operators and service companies. In situations where the well is being extended beyond casing that has earlier been run and cemented, there occur situations depending on the properties of the drilling mud or the formation where the making of more hole with a drill bit at the end of a drill string beyond the end of the casing results in undesirable deposits on the existing casing. It is advantageous to remove such deposits for many reasons not least of which is to allow smooth and rapid entry of other tools or strings through the casing without getting hung up or stuck. In the past the drill string assembly was pulled out of the hole (POOH) and a separate trip was run with scraping equipment.
Generally the scraping equipment was retained in a retracted position with one set of springs and when the desired start point for scraping was reached a different set of springs was released to allow the scrapers to extend into scraping position. These designs went in without rotation and were generally considered ill-suited for the present invention of a one trip method of drilling and scraping a casing on pulling out of the hole. Accordingly, the apparatus that supports the method has incorporated a retention and release system for the scrapers that integrates operation of a ported sub to enable circulation when scraping to enhance the removal capabilities. In several alternatives the circulation can be optional or can be directed in tandem to the annulus and some to the bit still in the hole or entirely to the annulus near the scrapers and bypassing the drill bit altogether.
Relevant background art to the present invention as claimed in the claims is a circulation sub that has two sleeves that allows sequential operation of two movements to allow opening and then closing a port in a ported sub. This design is described in U.S. Pat. No. 7,954,555. US 2010/0243257 shows a releasable scraper. Scrapers are generally described in US 20100096122 and US 20110265988.
The present invention is focused on a one trip method to drill and then scrape as the bit comes out of the hole as well as devices that make the method possible. In one variation the scraper and stabilizers are part of the drill string that can further optionally include a closed ported sub so that circulation for drilling goes through the drill bit. When drilling is done and the bit is POOH the drill string receives an object to allow powering a piston that releases the scrapers. The object is then allowed to pass further to a circulation sub to open a circulation port so that circulation with scraping can go on as the drill bit is removed. Shifting the piston passes the object further downhole for operation of the circulation sub to the open position. High circulation rates can be achieved and the configuration can allow some flow to go to the bit or to bypass the bit completely. In a preferred alternative a single sleeve releases the scrapers which are retained externally to a mandrel with stabilizers. Sleeve shifting shears retainers and opens circulation ports. A bypass for the dropped ball landed on the seat of the sleeve piston also opens on shifting of the sleeve to enable circulation flow that bypasses the blocking object. These and other aspects of the present invention will be more readily apparent to those skilled in the art from a review of the description of the preferred embodiment and the associated drawings while recognizing that the full scope of the invention is to be determined from the appended claims.